Intra-oral devices which are applied to persons' dental arches, both orthodontic and non-orthodontic devices, have historically been made by casting a dental arch model from an impression of a person's dental arch and then fabricating the device on the cast arch model. Such a process is largely labor-intensive.
An arch impression, either total or partial, is typically taken at a dental office. While the device fabrication process can be completed at the dental office, an alternative is to send an arch impression to a dental laboratory where the process is completed, after which the finished device is sent to the dental office.
A significant factor in a dentist's decision to use a dental laboratory in that way is fabrication cost because use of technicians in a dental laboratory to fabricate an intra-oral device is likely to be more economical.
A more recent process for fabricating an intra-oral device utilizes 3-D printing to fabricate a dental arch model. An electronic scan of a person's arch is performed to create a data file which can be transmitted to a dental laboratory which has 3-D printing equipment for fabricating a dental arch model from the data file.
There are a number of commercial sources for 3-D scanners for scanning a person's arch, for software for converting a scan into a program for a 3-D printer, and for 3-D printers.
The 3-D printing process creates a 3-D model by a layering process in which each successive layer is laid down on top of a preceding one, thereby building the model one layer at a time. While each layer has a finite thickness which can be very small, the nature of the process may result in the layering having surface grooves because of non-congruence of perimeters of successive layers. While making the layers thinner reduces the size of the surface grooves, the length of time needed to fabricate a model may increase because of the need to increase the number of layers. Because the length of time for which a 3-D printer is in use affects the economics of creating a model, reducing the size of the surface grooves in that way may increase fabrication cost.
If the surface grooves in a printed arch model are significant enough to be considered imperfections, it may be necessary for a technician to manually work on the model using suitable tools to eliminate, or at least minimize, the imperfections. The amount of labor to do so is also a contributor to fabrication cost.
The costs associated with use of a 3-D printer for creating a model and any subsequent technician work on the model may therefore be seen to be a function of the degree of accuracy which is needed in a finished appliance. For certain appliances a high degree of accuracy may be needed to achieve acceptable functionality of the appliance and comfort of a person using a particular appliance.